Preparation and evaluation of thin ZSM-5 membranes synthesized in the absence of organic template molecules

Porous alpha -alumina supports with a pore size of 100 nm were seeded with colloidal TPA-silicalite-1 crystals with a size of 120 nm. The seeded supports were calcined and treated in a synthesis solution free from organic template molecules to form ZSM-5 films on the supports. According to SEM images, the films were about 2 mum thick and no defects could be found on the as-synthesized membranes. Single gas permeation data was collected and good quality membranes (defined as having a non-detectable permeance of SF6 after drying at 100 degreesC) were further evaluated using binary/ternary gas mixtures. The selectivity for n-butane/i-butane had a maximum value of 17.8 at 220 degreesC. Water was selectively separated from a helium-diluted vaporized water/ethanol azeotrope with a maximum selectivity of 12.4. (C) 2001 Elsevier Science B.V. All rights reserved.